Image range expansion control methods and apparatus

• US 10,395,351 B2
• Filed: 10/24/2016
• Issued: 08/27/2019
• Est. Priority Date: 04/08/2011
• Status: Active Grant

• Current Assignee: Dolby Laboratories Licensing Corporation (Dolby Laboratories Incorporated)
• Original Assignee: Dolby Laboratories Licensing Corporation (Dolby Laboratories Incorporated)
• Inventors: Atkins, Robin, Margerm, Steve
• Primary Examiner(s): Patel, Shivang I
• Application Number:
  US15/332,454
• Publication Number:
  US 20170039690A1
• Time in Patent Office: 1,037 Days
• Field of Search: 345581
• CPC Class Codes: G06T 2207/10024 Color image
• CPC Class Codes: G06T 2207/20008 Globally adaptive
• CPC Class Codes: G06T 2207/20208 High dynamic range [HDR] image processing
• CPC Class Codes: G06T 5/92 based on global image properties
• CPC Class Codes: G06V 40/162 using pixel segmentation or colour matching
• CPC Class Codes: G09G 2320/0271 Adjustment of the gradation levels within the range of the gradation scale, e.g. by redistribution or clipping
• CPC Class Codes: G09G 2320/066 for control of contrast
• CPC Class Codes: G09G 2320/0673 for control of gamma adjustment, e.g. selecting another gamma curve
• CPC Class Codes: G09G 2320/08 Arrangements within a display terminal for setting, manually or automatically, display parameters of the display terminal
• CPC Class Codes: G09G 2340/04 Changes in size, position or resolution of an image
• CPC Class Codes: G09G 2340/0428 Gradation resolution change
• CPC Class Codes: G09G 2340/06 Colour space transformation
• CPC Class Codes: G09G 2370/04 Exchange of auxiliary data, i.e. other than image data, between monitor and graphics controller
• CPC Class Codes: G09G 5/04 using circuits for interfacing with colour displays
• CPC Class Codes: G09G 5/10 Intensity circuits
• CPC Class Codes: H04N 21/4854 for modifying image parameters, e.g. image brightness, contrast
• CPC Class Codes: H04N 21/84 Generation or processing of descriptive data, e.g. content descriptors systems specially adapted for using meta-information in broadcast systems H04H60/73

Abstract

Image data is adjusted for display on a target display. Maximum safe expansions for one or more attributes of the image data are compared to maximum available expansions for the attributes. An amount of expansion is selected that does not exceed either of the maximum safe expansion and the maximum available expansion. Artifacts caused by over expansion may be reduced or avoided.

Claims

1. An apparatus for image range expansion, the apparatus comprising:

a decoder that obtains image data and metadata from a stored data stream, the metadata includes both;

(i) information for luminance dynamic range expansion for at least a portion of the image data; and

(ii) characteristics of a source display, the characteristics of the source display including one or more parameters identifying color primaries, a first luminance level, and second luminance level of the source display;

a dynamic range expander that safely remaps the image data from source display dynamic range, as indicated by the first luminance level and the second luminance level identified in the characteristics of the source display, to fit within a dynamic range of a target display, based on the metadata; and

a color gamut expander that safely remaps the image data from source display gamut to fit within a color gamut of a target display, based on the metadata;

wherein the image data as safely remapped is caused to be rendered on the target display.

2. The apparatus of claim 1 wherein an interface is used to interrogate the target display for target display information.

3. The apparatus of claim 1 wherein the first luminance level is a white level for the source display.

4. The apparatus of claim 1 wherein the second luminance level is a black level for the source display.

5. The apparatus of claim 1 wherein the portion is a video scene of the image data.

6. A method for image range expansion, the method comprising:

obtaining, by a decoder, image data and metadata from a stored data stream, the metadata includes both;

(i) information for luminance dynamic range expansion for at least a portion of the image data; and

(ii) characteristics of a source display, the characteristics of the source display including one or more parameters identifying color primaries, a first luminance level, and second luminance level of the source display;

safely remapping, by a dynamic range expander, the image data from source display dynamic range, as indicated by the first luminance level and the second luminance level identified in the characteristics of the source display, to fit within a dynamic range of a target display, based on the metadata;

safely remapping, by a color gamut expander, the image data from source display gamut to fit within a color gamut of a target display, based on the metadata;

wherein the image data as safely remapped is caused to be rendered on the target display.

7. The method of claim 6, wherein an interface is used to interrogate the target display for target display information.

8. The method of claim 6, wherein the first luminance level is a white level for the source display.

9. The method of claim 6, wherein the second luminance level is a black level for the source display.

10. The method of claim 6, wherein the portion is a video scene of the image data.

11. A non-transitory computer-readable medium storing a sequence of instructions, which when executed by one or more computing processors, causes the one or more computing processors to perform:

obtaining, by a decoder, image data and metadata from a stored data stream, the metadata includes both;

(i) information for luminance dynamic range expansion for at least a portion of the image data; and

(ii) characteristics of a source display, the characteristics of the source display including one or more parameters identifying color primaries, a first luminance level, and second luminance level of the source display;

safely remapping, by a dynamic range expander, the image data from source display dynamic range, as indicated by the first luminance level and the second luminance level identified in the characteristics of the source display, to fit within a dynamic range of a target display, based on the metadata; and

safely remapping, by a color gamut expander, the image data from source display gamut to fit within a color gamut of a target display, based on the metadata;

wherein the image data as safely remapped is caused to be rendered on the target display.

12. The medium of claim 11, wherein an interface is used to interrogate the target display for target display information.

13. The medium of claim 11, wherein the first luminance level is a white level for the source display.

14. The medium of claim 11, wherein the second luminance level is a black level for the source display.

15. The medium of claim 11, wherein the portion is a video scene of the image data.